PROJECT SUMMARY (See instructions) The Mouse Histology and Phenotyping Laboratory (MHPL) provides the Northwestern University research community with histopathology assessment of murine tissues by trained pathologists and comprehensive histology services performed by expert histotechnologists. In addition, training is provided for investigators to learn to detect gross anomalies in rodents, to harvest tissue from various organ systems and to perform immunohistochemical and special histological stains on tissue sections generated by the MHPL. The MHPL was developed to fulfill a need by the investigative community to assist with the analysis of new murine models, to leverage the expertise of pathologists in the histopathological assessment of tissue anomalies and neoplasms, and to increase the likelihood of extracting meaningful phenotypic information to guide future investigations. Murine tissue has histological characteristics distinct from human tissue and therefore accurate interpretation requires microscopic examination by.pathologists with an understanding of disease pathobiology, rodent histopathology and murine development. Moreover, tissue isolation, processing, and sectioning often require the involvement of highly skilled histotechnologists, especially when embryonic lethal phenotypes or complex developmental abnormalities are to be studied. The MHPL is directed by an anatomic pathologist and neuropathologist with more than twenty years of experience in diagnosing human tumors and developmental abnormalities. He has equally extensive training in rodent adult and developmental pathobiology and histopathology. Other members ofthe MHPL staff include a second fulltime associate pathologist, three full-time ASCP certified histotechnologists, two part-time histotechnologists and two part-time technical/administrative assistants. Together, this team provides a broad range of technical and diagnostic services to investigators throughout the Northwestern University research enterprise in a high-volume and fast-paced environment. These comprehensive histopathology support services enhance the ability of our Cancer Center investigators to characterize viable and embryonic lethal mouse models and to develop and analyze new in vivo model systems to study cancer biology.